Distilling Essential Oils: Freshen Air with Menthol

Desiree Bell is inspired by botanicals and natural materials. She is a vegetarian who has a certificate in herbal studies and a certificate from Australasian College of Health Sciences in Aromatherapy. Visit her blogBeyond A Garden.

Peppermint (Mentha ×pipertia) is one of the most widely known mint species in North America. Peppermint, which does not produce seed, is a sterile hybrid of spearmint (Mentha spicata) and water mint (Mentha aquatica). Commercial growers plant peppermint from certified rootstock, and once planted it regrows each year. Most growers rotate peppermint with other crops on a three- to four-year cycle.

Commercial growers in the northwest harvest and distill their peppermint crops in the months of July and August. After the plant is cut it cures in windows for several days, allowing moisture to evaporate from the leaves. Then the dry peppermint is chopped and blown directly into a distilling tub that is mounted on a truck or trailer.

The tub is then taken to a distillery where live steam under pressure is applied to the chopped peppermint in the sealed tub to extract the essential oil. The steam and vaporized oil then pass into a coil where the mixture is cooled and condensed. The water and oil then flow into a separator where the natural difference in density separates the oil from the heavier water.

The pure peppermint oil is tapped off the top into a 55-gallon storage drum. One drum can flavor 5 million sticks of gum or 400,000 tubes of toothpaste. It takes approximately 10,000 pounds of the dry peppermint plant to yield about 84 pounds of peppermint oil. The peppermint oil is sold to a “handler” who blends oils from different locations to the specification of the end user so the taste is consistent.

Photos by Desiree Bell

Besides gum and toothpaste, peppermint oil is used for ice cream, candy, cookies and pharmaceutical flavorings. It is also used medicinally for indigestion, nausea, sore throat, diarrhea, headaches and toothaches.

The waste water from the distillation process can be recycled to feed the boiler to make steam for processing the next batch of peppermint oil or it can be bottled (preferably organic) and used as a hydrosol. Peppermint hydrosol can be spritzed on the face during hot weather to rehydrate the skin; and due to the chemical component menthol, peppermint can also be used as a compress for inflammation.